Twisting elusive quantum particles with a quantum computer
Quantum processor provides insights into exotic states of matter
Date:
December 2, 2021
Source:
Technical University of Munich (TUM)
Summary:
While the number of qubits and the stability of quantum states
are still limiting current quantum computing devices, there are
questions where these processors are already able to leverage their
enormous computing power. Scientists used a quantum processor to
simulate the ground state of a so-called toric code Hamiltonian --
an archetypical model system in modern condensed matter physics,
which was originally proposed in the context of quantum error
correction.
FULL STORY ========================================================================== While the number of qubits and the stability of quantum states are still limiting current quantum computing devices, there are questions where
these processors are already able to leverage their enormous computing
power. In collaboration with the Google Quantum AI team scientists
from the Technical University of Munich (TUM) and the University of
Nottingham used a quantum processor to simulate the ground state of a
so-called toric code Hamiltonian - - an archetypical model system in
modern condensed matter physics, which was originally proposed in the
context of quantum error correction.
==========================================================================
What would it be like if we lived in a flat two-dimensional
world? Physicists predict that quantum mechanics would be even stranger
in that case resulting in exotic particles -- so-called "anyons" --
that cannot exist in the three- dimensional world we live in. This
unfamiliar world is not just a curiosity but may be key to unlocking
quantum materials and technologies of the future.
In collaboration with the Google Quantum AI team scientists from the
Technical University of Munich and the University of Nottingham used a
highly controllable quantum processor to simulate such states of quantum matter. Their results appear in the current issue of the scientific journalScience.
Emergent quantum particles in two-dimensional systems All particles in our universe come in two flavors, bosons or fermions. In the three-dimensional world we live in, this observation stands firm. However, it was
theoretically predicted almost 50 years ago that other types of particles, dubbed anyons, could exist when matter is confined to two dimensions.
While these anyons do not appear as elementary particles in our universe,
it turns out that anyonic particles can emerge as collective excitations
in so- called topological phases of matter, for which the Nobel prize
was awarded in 2016.
"Twisting pairs of these anyons by moving them around one another in the simulation unveils their exotic properties -- physicists call it braiding statistics," says Dr. Adam Smith from the University of Nottingham.
A simple picture for these collective excitations is "the wave"
in a stadium crowd -- it has a well-defined position, but it cannot
exist without the thousands of people that make up the crowd. However, realizing and simulating such topologically ordered states experimentally
has proven to be extremely challenging.
Quantum processors as a platform for controlled quantum simulations
In landmark experiments, the teams from TUM, Google Quantum AI, and
the University of Nottingham programmed Google's quantum processor
to simulate these two-dimensional states of quantum matter. "Google's
quantum processor named 'Sycamore' can be precisely controlled and is a well-isolated quantum system, which are key requirements for performing
quantum computations," says Kevin Satzinger, a scientist from the
Google team.
The researchers came up with a quantum algorithm to realize a state with topological order, which was confirmed by simulating the creation of
anyon excitations and twisting them around one another. Fingerprints from long-range quantum entanglement could be confirmed in their study. As a possible application, such topologically ordered states can be used to
improve quantum computers by realizing new ways of error correction. First steps toward this goal have already been achieved in their work.
"Near term quantum processors will represent an ideal platform to explore
the physics of exotic quantum phases matter," says Prof. Frank Pollmann
from TUM.
"In the near future, quantum processors promise to solve problems
that are beyond the reach of current classical supercomputers." ========================================================================== Story Source: Materials provided by
Technical_University_of_Munich_(TUM). Note: Content may be edited for
style and length.
========================================================================== Journal Reference:
1. K. J. Satzinger, Y.-J Liu, A. Smith, C. Knapp, M. Newman,
C. Jones, Z.
Chen, C. Quintana, X. Mi, A. Dunsworth, C. Gidney, I. Aleiner,
F. Arute, K. Arya, J. Atalaya, R. Babbush, J. C. Bardin, R. Barends,
J. Basso, A.
Bengtsson, A. Bilmes, M. Broughton, B. B. Buckley, D. A. Buell, B.
Burkett, N. Bushnell, B. Chiaro, R. Collins, W. Courtney,
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Kim, P. V. Klimov, A. N. Korotkov, F. Kostritsa, D. Landhuis,
P. Laptev, A. Locharla, E. Lucero, O. Martin, J. R. McClean,
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Petukhov, N. C. Rubin, D. Sank, V. Shvarts, D. Strain, M. Szalay, B.
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M. Knap, F. Pollmann, P. Roushan. Realizing topologically ordered
states on a quantum processor. Science, 2021; 374 (6572): 1237 DOI:
10.1126/ science.abi8378 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2021/12/211202153927.htm
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